1. Field of the Invention
The invention relates to a developer holding body for holding a developer and a developing apparatus having such a developer holding body.
2. Related Background Art
A developing apparatus having a developer holding body for holding a developer has been disclosed in JP-A-10-48940. According to such an apparatus disclosed therein, in order to develop an electrostatic latent image formed on an electrostatic latent image holding body by using a developer, after the developer is temporarily held on the developer holding body, the developer holding body is come into contact with the electrostatic latent image holding body, so that the developer held on the developer holding body is supplied onto the electrostatic latent image holding body.
A rough surface is formed on the developer holding body in order to obtain excellent holding characteristics of the developer and its surface shape is shown by unidirectional indices such as: 10-point average roughness Rz showing an interval value between an average of points in a range from a vertex of the largest value to a vertex of the fifth largest value in a roughness curve and an average of points in a range from a bottom point of the minimum value to a bottom point of the fifth minimum value; arithmetic average roughness Ra showing an average of absolute values of height differences between an average line and the roughness curve; an average interval Sm of the rough portions indicative of an interval value between a change point where the roughness curve changes from a mountain to a valley and the next change point; and the like.